The present invention relates particularly to clamps, this term being generally understood to refer to fastening mechanisms used to join, grip, support, or compress mechanical or structural parts.
Clamps generally include parts which are moved together by screws to hold or compress mechanical or structural parts. Tightening the screw brings the clamping surfaces together into a position where they are able to grip or support the desired item or element.
Commonly clamps are used to hold items together during manufacture or building.
One common example is the use of clamps to hold together tubes or pipes. These may include a substantially semi circular or circular portion with flanges, the flanges are then tightened towards one another by a screw or other fastening means, to clamp the semi circular portion around the tube, pipe or other item. This has a number of significant disadvantages, one being the protruding portions, which may easily catch on objects or injure people within the vicinity.
Another significant problem is that clamps can be very slow to do up and unwind.
Additionally such mechanisms, for example KeeKlamp™, often rely on the correct insertion, rotation, and tensioning of one or more threaded elements. If the threaded element is insufficiently tightened the mechanism is prone to loosen with use/vibration. When correctly used the axial length of the threaded element, often a “set-screw”, need to be lengthened, with in a narrow range, as if over stretched the threads will strip, and if under stretched the fastener may fail with use/vibration.
Many clamps also make use of standard bolts. This may be undesirable in structural situations where nuts and bolts are susceptible to jiggling loose, or shearing under the pressures applied. In industrial situations it is very important that the fixing is secure, as failure could lead to injury or death to people in the vicinity. For example a screw or bolt if insufficiently tightened may allow the components to telescope or rotate under load or stress.
Clamps are also commonly used in products where the length is changeable, for example ladders, scaffolding, props in the building industry, bicycle seat posts, furniture, walking canes, tent poles to name a few.
The applicants have previously (PCT/NZ2004/000132) developed a mechanism to secure at least one element, which may be telescoping, relative to another element.
PCT/NZ2004/000132 discloses a securing apparatus of a substantially circular circumference, with a deformable body, a slot extending longitudinally along a portion of the apparatus and an aperture in the slot.
This is an auto locking friction mechanism which has an inherent flexibility where the locking element may be expanded or contracted using a tool, heat or other physical means. The elasticity of the mechanism material allows this expansion or contraction to occur and when contracted the mechanism applies a relative and generally opposite force to the element being secured or aligned.
When a releasing tool is applied to the aperture, the slot is widened and opened to allow movement of the telescoping, or other elements being secured. When the releasing tool is removed the deformable body reverts to its original position to provide a secure interference fit to the elements it is attached to.
Unless a long slot along a significant portion or all of the length of the clamp body is used, a further aperture may be positioned at one end of the slot to decrease the stress on the body at the point where the slot ends. Alternatively, a side slot extending around the body, may be used instead, however, this may considerably weaken the body of the clamp.
However this type of clamping mechanism can be improved.
One area for improvement is that the slot leads to the formation of a point of weakness. The point of weakness will occur at the point where the body starts to be deformed by use of the release tool. Opening the slot will lead to the body being forced open at one spot on the body.
This point of weakness may lead to a gradual decrease in the efficiency of the apparatus to secure elements reliably. This would especially be the case on elements which are regularly moved, in this instance weakening, fatigue and breaking of the securing mechanism may occur.
This point of weakness occurs due to the releasing tool having a greater effect near the point of use of the tool. As the securing mechanism relies on an interference fit, this may also lead to poor assembly and/or subsequent failure, or leakage of gas or fluid.
Further, if the slot is not opened up sufficiently or has a non-uniform gap the element over which it must fit may foul the inside of the apparatus. This can lead to the user having to take care when operating the mechanism.
Also the element being clamped may only have clearance between the element and the securing mechanism within the close vicinity of the releasing tool being used. This may increase fouling the inside of the mechanism, and difficulty of use, and adjustment of the elements being held in relation to one another.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.